Adjustable choke attachment for shotguns



Aug. 3, 1954 A. E. scHRoEDER ADJUSTABLE CHOKE ATTACHMENT FOR SHOTGUNS 2 Sheets-Sheet l Filed May l, 1955 INVENTOR.

Aug. 3, 1954 A, E. scHRoEDER ADJUSTABLE CHOKE ATTACHMENT F'OR SHOTGUNS 2 Sheets-Sheet 2 Filed May lI 1955 allg',

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zuwibfliy )Nl/ENTOR. AELC E' 5c H @CEOE/Q Patented Aug. 3, 1954 ADJUSTABLE CHOKE ATTACHMENT FOR SHOTGUNS Arlo E. Schroeder, Newton, Kans., assigner to Flex-Prop Corporation, Inc., Marion, Kans., a corporation of Kansas Application May 1, 1953, Serial No. 352,399

(Cl. Ll2'l9) 4 Claims.

This invention relates to choke attachments for shotguns and more particularly to a variable chokey attachment which is automatically adjusted in response to successive shots from the associated gun.

It is among the objects of the invention to provide an improved shotgun attachment which can be easily mounted on the muzzle end of a shotgun barrel and will vary the choke of the barrel from the original form or condition to a full choke condition; which is adjustable to intermediate choke conditions between a no-choke and a fullchoke condition; which may be automatically adjusted from its no-choke condition to conditions of successively increasing choke by successive pulls on the gun trigger and may be similarly adjusted by other manually operated means without pulling the trigger; which can be connected to and disconnected from the gun trigger at will; which is effective on a gun barrel which actuates the breech mechanism of the gun by recoil of the barrel and does not interfere in any way with the operation of such a barrel; which does not interfere with the aiming or sighting of the associated gun; and which is simple and durable in construction, economical to manufacture, easy to install, and positive and effective in operation.

Other objects and advantages will become apparent from a consideration of the following description and the appended claims in conjunction with the accompanying drawings wherein:

Figure 1 is a fragmentary side elevational View of a shotgun with a choke varying attachment illustrative of the invention operatively mounted thereon;

Figure 2 is a fragmentary cross sectional View on an enlarged scale on the line 2--2 of Figure 1;

Figure 3 is a side elevational view of the portion of the mechanism illustrated in Figure 2;

Figure 4 is a perspective View on an enlargedV scale of the mechanism. illustrated in Figures 2 and 3;

Figure 5 is a transverse cross sectional View on the line 5-5 of Figure 1;

Figure 6 is a fragmentary longitudinal cross sectional Viewv on the line 6-6 of Figure 5;

Figure '7 is a fragmentary cross sectional view similar tol Figure 6 showing structural details of the mechanism illustrated in Figure 6; and

Figure 8 is an exploded perspective view of the portion of the mechanism illustrated in Figure 6.

With continued reference to the drawings, the shotgun fragmentarily illustrated in Figures l and 6 comprises a gun stock having a grip portion |50' at the front end ofthe stock, a forearm I l extending forwardly from the grip portion I9, a barrel i2 bedded in the normally upper surface of the forearm Il, a receiver I3 mounted on the forearm at the rear end of the barrel and containing the breech mechanism of the gun, a trigger guard lll mounted on and depending from the forearm at the end of the forearm adjacent the grip l 9, and a trigger l5 pivotally mounted in the breech mechanism of the gun and depending through an opening I 6 in the forearm into the trigger guard lll.

As the shotgun may be of a construction well known to the art, a further illustration and description thereof is considered unnecessary for the purposes of the present disclosure.

The gun barrel I2 is externally screw threaded near its muzzle end, as indicated at I8, and a sleeve structure, generally indicated at 2Q, receives the muzzle end portion of the gun barrel and is threaded onto the screw threads I8 on the gun barrel This sleeve 20 includes an intermediate portion 2! of cylindrical shape which closely receives the muzzle end portion of the gun barrel and is provided with internal screw threads threadedly engaging the screw threads i3 on the gun barrel and at its front end with an annular shoulder 22 of a width equal to the thickness of the gun barrel at the muzzle end of the latter which shoulder overlies and bears against the muzzle end of the barrel. The sleeve 20 fur.- ther includes a rear portion 23 of partly conical shape having a bore which closely receives the corresponding portion of the gun barrel and having its thicker end at the rear end of the intermediate portion 2E and providing an external annular shoulder 24 extending entirely around the sleeve. The rear portion 33 of the sleeve tapers from the shoulder 24 to a featheredge at the rear end. of the sleeve, so that the rear end of the sleeve is brought down substantially to the outer surface of the associated gun barrel. The sleeve 20 alsoincludes a forward portion 25 of cylindrical shape extending forwardly from the shoulder 22 coaxially of the intermediate portion 2! and provided with longitudinally extending slots 26 equally spaced around the sleeve portion and dividing the sleeve portion into a plurality of longitudinally extending spring ngers 2l. Each of the spring lingers 2l is provided on its outer surface with a ramp, as indicated at 28, which ramps extend longitudinally of the corresponding lingers medially of the Width thereof and are provided with transversely concave outer surfaces and taper in thickness from their front ends located near the front ends of the corresponding iingers to their rear ends located near the shoulder 22. A housing 30 of cylindrical shape circumspatially surrounds the sleeve 2| from the shoulder 24 to the front end of the front portion 25 of the sleeve and is provided at its rear end with a thickened annular portion 3| provided with internal screw threads which engage with external screw threads 32 on the sleeve 2| adjacent the shoulder 24 to secure the housing on the sleeve. At its front end the housing is coterminous with the front end of the sleeve, and an annular plate or washer 33 is mounted on the front end of the sleeve portion 25 and within the front end of the housing 3) and closes the annular space between the housing and the sleeve, this end plate being rigidly secured to the housing, but being free of the sleeve, so that the front ends of the spring fingers 21 of the sleeve can move inwardly and outwardly relative to the inner edge of the annular end plate 33.

A` plunger, generally indicated at 35, is slidably mounted on the front and intermediate portions of the sleeve 2S and comprises end rings 36 and 31 of rectangular cross sectional shape disposed in coaxial and spaced apart and substantially parallel relationship to each other, and struts 38 of flattened shape extending between and secured at their opposite ends to the rings 36 and 3l' to hold the rings in position relative to each other, these struts being disposed in spaced apart and substantially parallel relationship to each other and being spaced at substantially equal angular intervals around the end rings. Both of the end rings 36 and 3? have substantially the same outside diameter, but the front end ring 33 has an inside diameter less than the inside diameter of the end ring 3l and it will be noted that the front end portion 25 of the sleeve 29 is of reduced diameter relative to the intermediate portion 2| and is joined at its rear end to the front end of the intermediate portion by a beveled annular shoulder 39.

When the plunger 35 is slidably mounted on the sleeve 2G, it is disposed in the annular space between the sleeve 23 and the housing 30 with the front ring 26 closely encircling the outer surface of the front portion 25 of the sleeve 2B, and the rear ring 31 closely encircling the outer surface of the intermediate portion 2| of the sleeve. The front ring 36 is provided at substantially equal angular intervals around the inner surface thereof with recesses and bearing balls 40 of hardened material are mounted one in each of the recess in the front ring 3E and each ball rides in the grooved outer surface of a corresponding ramp 23 on the front sleeve portion 25, and a compression spring 42 surrounds the intermediate portion 2| of the sleeve between an internal annular shoulder 43 near the rear end of the housing 3Q and the rear ring 31 of the plunger 35 and resiliently urges the plunger in a forward direction to move the front ring 36 of the plunger outwardly of the front portion 25 of the sleeve and the bearing balls 4B outwardly along the corresponding ramps 2B to move the spring fingers 2l toward each other and contract the front end portion of the sleeve portion 25 to thereby increase the choke at the muzzle end of the gun.

The housing 3G is provided in its under side with an opening 45 registering with the outer surface of the bottom strut 38 of the plunger 35 and the strut 33 is provided with notches 43 and 4l spaced apart therealong, each of the notches having an abrupt rear end disposed substantially radially of the plunger and having a forwardly and outwardly inclined surface extending from the inner limit of the rear end surface thereof.

A latch 48 of somewhat triangular shape is pivotally mounted at its forward, apical end on the housing 33 at the front end of the opening i5 in the housing and has its rear corner 48 disposed inwardly of the choke varying assembly shaped to engage in the notches 45 and 4l in the plunger strut 38 to releasably hold the plunger at selected positions of adjustment longitudinally of the sleeve 2D. A cover 5! attached to the housing 3G covers the opening 45 in the housing and the sear 48 and a spring 5| connected between this cover and the Sear resiliently urges the sear to its notch engaging position, as illustrated in Figures 6 and 7.

The latch 48 is provided with a recess 53 opening to the outer side and to the rear, base end thereof, and with'inclined longitudinally curved slots, as indicated at 55, in the walls thereof at the opposite sides of the recess 53, the slots being in registry with each other transversely of the scar.

A bell crank lever 55 is pivotally mounted at its angle on a pivot pin 55 mounted in the cover 5B and having one leg 5l extending outwardly from the pivot pin 53 and its other leg 58 extending forwardly from the pivot pin and entering the recess 53 in the rear end of the latch 48. The pivotal connections between the latch 48 and the lever 55 have their axes substantially in parallel planes disposed perpendicular to the longitudinal center line of the gun barrel I2 and the choke sleeve 20.

A spring 6@ connected between the lever 55 and the housing 3E) at the rear of the opening 45 in the housing resiliently urges the lever 55 about its pivot pin 55 in a direction to move the distal end of the outwardly extending leg 5l of the lever forwardly and the distal end of the forwardly extending leg 58 of the lever inwardly of the associated mechanism.

An abutment pin 6| extends transversely through the latch 48 and is received at its ends in the slots 5| in the sear and a spring 62 connected between this abutment pin and the sear resiliently urges the pin 6| to a position at the outer ends of the slots 5|, as illustrated in Figure '7.

A pull cord 64 is pivotally connected at its front end to the lever 55 at the distal end of the lever leg 53 and extends from the lever 55 rearwardly along the gun barrel E2 and forearm The housing 3B is provided with a pair of closed slots 63 extending longitudinally of the housing at substantially diametrically opposite locations therearound and each spaced approximately degrees circumferentially of the housing from the housing opening 45. Cocking pin-s 65 and 66 extend one through each of the slots 64 and have reduced and externally screw threaded inner end portions threaded into tapped holes, as indicated at 5l, in the rear ring 3l of the plunger in a manner such that the cooking pins project radially outwardly from the housing 3l). The mechanism is cocked by moving the plunger 35 rearwardly by manual pressure on one or both of the cooking pins E5 and 66 until the latch 48 is engaged in the notch 48 nearest the front end of the plunger and the compression spring 42 is fully compressed. Under these conditions, the split, frontY end portion 2-5 of the choke sleeve 2i isV inA a nc-choke condition.

With the choke mechanism cocked, as described above, a rearward pull on the pull cord 64 will pull the leg 51V ofthe lever 55 rearwardly, and the leg 58 of this lever outwardly against the abutment pin 6I and will move the Sear 48 outwardly to release the sear from the notch 46 in the plunger strut 38. The spring 42 will then movethe plunger forwardly, and the engagement of the balls 46 with the ramps 28 will compress the choke portion 25 of the choke sleeve and increase the choke at the muzzle end of the gun barrel. As soon as the latch 48 has been moved outwardly to an extent such that it is released from the notch in the plunger strut 38', the distalA end of the leg 58 of the lever 55 passes by the abutment pin 6I releasing the sear, so that the spring 5I swings the sear inwardly immediately and engages the sear with the next notch 41 in the plunger strut 3B to hold the plunger in an intermediate choke position. As soon as the rearward pulling force is released on the pull cord 64, the lever 55 is swung by the spring 60 to move the lever leg 51 forwardly and the lever leg 58 inwardly. When the distal end of the lever leg 58y strikes the abutment pin 6I, this pin is moved along the slots 5I against the force of spring 62 until the lever leg 5s again passes the abutment pin, but in the opposite direction, whereupon the spring 52 returns the abutment pin to the outer ends of the slots 5I where it is again engaged by the lever leg 58 when a subsequent rearward pull is exerted on the pull cord E4. Whenl the pull cord 64 is again pulled rearwardly, the sear is released from the notch 41, in the manner described above, and the spring 42 moves the plunger 35 forwardly to its full-choke position, the bearing balls 4I) being then disposed near the thicker front ends of the corresponding ramps 28.

With this arrangement, the choke of the gun barrel is successively increased in a step by step manner, so that the range of the gun is increased and the scattering of the shot is reduced. This is of particular utility when a hunter is shooting at game, such as game birds, which iiy rapidly away from the hunter, and it is desirable to increase the range of the gun for successive shots at the birds.

The forearm I I of the gun is provided near the front end thereof withk a recess S8 of elongated rectangular shape opening to one side of the forearm and the open side of this recess is covered by a cover plate 59 which extends marginally beyond the openingand is secured to the forearm by suitable means, such as the screws 10. A U-shaped bracket 1I is disposed in the recess 68 and has spaced apart and substantially parallel straight legs 12 and 13 which extend longitudinally of the forearm and of which the leg 12 is disposed against the inner side of the cover plate 69. Guide staples 15 and 16 are mounted on the plate 59 at the inner side of the plate and in spaced apart relationship longitudinally of the plate, and these staples slidably receive the bracket leg 'i2 and support the bracket in the recess 63 for a limited freedom of forward and rearward movement. The bight portion 16 of the bracket 1I is disposed substantially at right angles to the plate 69 and near the rear end of the recess 68, and a pull cord 18 is secured at its front end to the bight portion 11 centrally of this bight portion and extends rearwardly through a bore 19 in the forearm to a f of the pull cord 64, as indicated at 38.

connection at its rear end with the gun trigger I5, as indicated at 80, so that the bracket 1I will be pulled rearwardly each time the gun trigger I5 is pulled to re the gun.

The cover plate 69 is provided with a substantially centrally located slot 8I extending longtudinally of the plate and a shaft 82 extends through this slot and is journaled in apertures provided in the legs 12 and 13 of the bracket 1I. The shaft 82 is disposed substantially perpendicular to the plate 69 and a wing 83 extends laterally from the shaft 82 at the outer side of the plate 69 for use in applying manual pressure to turn the shaft.

A tubular sheath 85 extends along the gun barrel l2 and through a bore in the front portion of the forearm II from the rear end of the cover Eil to the front end of the recess 68 in the forearm, and the pull cord 64 extends slidably through this sheath into the recess 58. A crank 8S projects laterally from the shaft 82 within the recess 68 and a longitudinally curved link 81 is pivotally connected at one end to the crank 86 and is connected at its other end to the rear end The link 81 extends across the shaft 82 and, when the shaft is in one rotational position, the link 81 holds the crank at this rotational position and connects the pull cord 64 to the bracket 1I in a manner such that when the bracket is pulled rearwardly by the trigger connected pull cord 18, the pull cord S4 is also pulled rearwardly and operates the choke increasing mechanism at the muzzle end of the gun barrel in the manner fully described above. The shaft can be rotated by the wing 83 to a position in which the pull cord 64 is functionally released from the bracket 1I, in which case the movement of the bracket 1I incident to gun firing movements of the trigger I5 will have no effect on the pull cord 64 or the choke varying mechanism at the muzzle end of the gun. When the pull cord 5s is so released from the bracket 1I, it may, however, be pulled to operate the choke varying mechanism by manually turning the shaft 32 to its position connecting the pull cord to the bracket and then plultlirsigT the shaft rearwardly longitudinally of the s o After the mechanism has been released to increase the choke, it is recocked by moving the pins and 6s rearwardly in the corresponding slot 54, as described above.

The invention may be embodied specic forms without departing from the spirit or essential characteristics thereof. The present embodiment is, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are, therefore, intended to be embraced therein.

What is claimed is:

l. In cembination with a shotgun having a forearm, a trigger and a barrel provided with external screw threads at its muzzle end, an adjustable choke attachment comprising a choke assembly threaded onto the muzzle end of said barrel and including spring means resiliently urging said assembly to its maximum choke condition, latch means stopping said spring means at selected conditions of progressively increasing choke of the assembly, and manually operated means effective to return said assembly from any in other setting providing a choke condition greater than the minimum choke condition of the assembly against the force of said spring means, flexible means connecting said latch means to said trigger for successively releasing said latch means upon successive gun firing movements of said trigger, and manually operated means mounted on said forearm and connected into said flexible means and effective to operatively disconnect said trigger from said latch means and to actuate said latch means independently of said trigger.

2. In combination with a shotgun having a forearm, a barrel bedded on said forearm and extending forwardly therefrom, and a trigger depending from said forearm near the breech end of said barrel, a choke bearing attachment mounted on the muzzle end of said barrel and including a choke sleeve receiving the muzzle end of said barrel and having a longitudinally split and circumferentially contractile portion extending forwardly from the muzzle end of said barrel, a plunger slidably receiving said choke sleeve, ramps disposed between said plunger and said longitudinally split sleeve portion effective to circumferentially contract said longitudinally split sleeve portion upon movement of said plunger longitudinally of said sleeve in one direction, spring means carried by said sleeve resiliently urging said plunger in said one direction, manually engageable means connected to said plunger for moving the latter in the other direction against the force of said spring means, latch means carried by said sleeve and effective to engage said plunger at spaced apart locations therealong and releasably hold said plunger at selected stages of its movement in said one direction from a 11o-choke to a full-choke position, and iiexible means connecting said latch means to said trigger for releasing said latch means successively upon successive gun ring movements of said trigger.

3. In combination with a shotgun having a forearm, a barrel bedded on said forearm and extending forwardly therefrom, and a trigger depending from said forearm near the breech end of said barrel, a choke bearing attachment mounted on the muzzle end of said barrel and including a choke sleeve receiving the muzzle end of said barrel and having a longitudinally split and circumferentially contractile portion extending forwardly from the muzzle end of said barrel, a plunger slidably receiving said choke sleeve, ramps disposed between said plunger and said longitudinally split sleeve portion effective to circumferentially contract said longitudinally split sleeve portion upon movement of said plunger longitudinally of said sleeve in one direction, spring means carried by said sleeve resiliently urging said plunger in said one direction, manually engageable means connected to said plunger for moving the latter ,in the other direction against the force of said spring means, latch means carried by said sleeve and effective to engage said plunger at spaced apart locations therealong and releasably hold said plunger at selected stages of its movement in said one direction from a no-choke to a fullchoke position, exible means connecting said latch means to said trigger for releasing said latch means successively upon successive gun firing movements of said trigger, and manually operated means connected into said flexible means and effective to functionally lengthen said flexible means to render said trigger ineffective to release said latch means.

4. In combination with a shotgun having a forearm, a barrel bedded on said forearm and extending forwardly therefrom, and a trigger depending from said forearm near the breech end of said barrel, a choke bearing attachment mounted on the muzzle end of said barrel and including a choke sleeve receiving the muzzle end of said barrel and having a longitudinally split and circumferentially contractile portion extending forwardly from the muzzle end of said barrel, a plunger slidably receiving said choke sleeve, ramps disposed between said plunger and said longitudinally split sleeve portion effective to circumferentially contract said longitudinally split sleeve portion upon movement of said plunger longitudinally of said sleeve in one di# rection, spring means carried by said sleeve resiliently urging said plunger in said one direction, manually engageable means connected to said plunger for moving the latter in the other direction against the force of said spring means, latch means carried by said sleeve and effective to engage said plunger at spaced apart locations therealong and releasably hold said plunger at selected stages of its movement in said one direction from a no-choke to a full-choke position, and flexible means connecting said latch means to said trigger for releasing said latch means successively upon successive gun firing movements of said trigger, said latch means being automatically disconnected from said trigger and re-set immediately upon its release from said plunger to re-engage said plunger at a different location therealong and being reconnected to said trigger upon release of the trigger after a gun firing movement thereof.

No references cited. 

